Power transmission device



June 1, 1937. PQwHncoM POYWEIR TRANSMISSION DEVICE Filed April '25, 1936 5 Sheets-Sheet 1 INVENTOR. Mai-0n whlfcom g a 59 TTORNEYS,

June 1, 1932. w T 2,082,433

POWER TRANSMIS S ION DEVICE Filed April 25-, 1936 5 Sheet-Sheet 2 I INVENTQR. Presfon Wkifqnm b June 1, 1937. P. WHlTCOMB POWER TRANsMI SION DEVICE Filed April 25, 19:56

5 Sheets-Sheet 4 Przs for! Whifcpmb POWER TRANSMISSION DEVI-CE,

Filed April 25, 1936 5 Sheets-Sheet 5 INVENTQR. Preston Wh "can: b

' ATTORNEYS,

Patented June I, 1937 UNITED STATES PATENT OFFICE POWER TRANSMISSION DEVICE Application April 25,

6 Claims.

This invention is concerned .with improvements in power transmission devices. While the invention is broadly applicable for the-purpose of transmitting power from a driver to a driven member with a speed reduction, it has been disclosed herein in theform of a hoist.

A basic object of the invention is to provide a power transmission mechanism employing a series of balls for interconnecting the driving and driven member, which operate in spiral grooves on the members whereby the balls are propelled by the driving member and in their movement cause a proportionate movement of the driven member.

Another object of this invention is to provide a mechanism of this general type in which either a single or a double reduction in speed is efiected as between the driving and driven member.

The further object of this invention, namely to provide an eflicient power transmission device, is attained by means of the novel ball drive herein employed. I

The many detailed objects of this inventio which are successfully secured thereby will become apparent in their full scope as the description of the structure and operation proceeds.

This invention resides substantially in the combination, construction, arrangement and relative location of parts, all as will be described in connection with the attached drawings.

In the accompanying drawings,

Figure l is a vertical, central, longitudinal view through one form of device in accordance with this invention, which form is specifically that of a hoist;

Figure 2 is a plan view with some parts broken away of the inner drive screw or worm shaft;

Figure 3 is a front elevational view of one of the thrust rings, two of which are employed;

Figure 4 is a cross sectional view taken on the line 4-4 of Figure 3; I

Figure 5 is a plan view of .one of the thrust plate members of which five are employed at each end of the device;

Figure 6 is a cross sectional view taken on the line' 66 of Figure 5;

Figure 7 is a longitudinal, central, cross sectional View through the intermediate worm member;

Figure 8 is an end elevational view thereof;

Figure 9 is an end elevational view of the inner guide sleeve; I

Figure 10 is a side elevational view thereof;'

1936, Serial No. 76,320

the guide sleeve plugs of which there are two in the device; I

Figure 12 is a cross sectional view taken on the line lZ-IZ of Figure 11;

Figure 13 is an end elevational view of the outer guide sleeve;

Figure 14 is a side elevational view thereof; I

Figure 15 is a cross sectional view taken on the line l5l5 of Figure 1;

Figure 16 is an enlarged cross sectional view on the line Iii-l6 of the other end thrust rin similar to that of Figure 4;

Figure 1''! is a front elevational view thereof;

Figure 18 is an end elevational view of the left hand section of the outer drum; and

Figure 19 is a central. longitudinal, cross sectional view therethrough.

Generally speaking the device of this invention consists of a mechanism by means of which power may be transferred from a driving to a driven member with high eificiency and at a great reduction in speed. To those skilled in the art it will be apparent that a device of this nature is particularly useful in a hoist mechanism, and for this reason the principles of the invention, although not limited to a hoist mechanism, have been shown embodied in such a structure. I

The hoist illustrated comprises a pairof end supporting plates or discs I and 2- which are provided with apertured lugs 3 and 4 respective-'- ly by which the mechanism may be suspended by any suitable means.

The plate I is provided with a small end cap 5 which closes a central passage therethrough. The other plate or end member 2 is constructed so as to form the end cover-for a motor casing 6 which has been illustrated for purposes of description as an electric motor for driving the hoist. The motor comprises diagrammatically the field magnet 1 provided with the field winding 1' and the armature 8. Supported in the ball bearings 9 at one end and in bearings not shown in the housing ID at the other end is a shaft II which may be secured to or form a continuation of the shaft of the armature 8. This shaft is provided witha continuous thread or worm H The thread or worm is of the configuration clearly apparent from Figure 2. It is a single left hand thread or worm having a one-half inch lead in the form of the device illustrated.

Mounted in each end or cover plate I and 2 are the guide sleeve plugs l2 and I4 respectively. These guide sleeve plugs comprise central sleeve like portions terminating in 'disc end members I2 and I 4 respectively. The tubular portion of the sleeve plug I2 is mounted and locked in the end plate I by means of the screw pin l3 and similarly the other is locked in the cover plate 2 by means of the screw pin I5. Thus the guide sleeve plugs are fixed in the end caps or memhers I and 2 against either sliding or rotating movement. Figures 11 and 12 show the guide sleeve plugs in full detail. These plugs, of which there are two, are exactly the same. The sleeve portion of the one illustrated has a hole I3 therein in position to be engaged by the screw pin la. The plate end I2 is provided with a counterbore or recess I2 in alignment 'with the bore in the sleeve. The face of the disc between the periphcry and the recess I2 is provided with a concave annular surface as illustrated at I2 The disc portion also has a series of holes I2 for a purpose to be described later.

At I6 is a sleeve which is slipped over the shaft II and within which the shaft rotates. This sleeve I6, as illustrated in Figures 9 and 10 has a series, flve actually, of slots I6 through the walls thereof and extending for a substantial portion of the length of the sleeve. The ends of the sleeve are provided with notches I6 in which the pins I I lie.. These pins are mounted in the holes IT in the guide sleeve plugs so as to project into the recess IN. The ends of the sleeve I6 fit into' the recesses I2 and are prevented from turning with the shaft II by reason of the engagement of the plus I! in the notches I6.

At I8 is the outer guide sleeve which is shown in full detail in Figures 13 and 14. It. is in-the form of a tube having a series, five in number, of slots l8 through the wall thereof and extending for a substantial portion of the length of the sleeve.

The sleeve is provided with several holes Ill which align with the bores I2 in the guide sleeve plugs so that the sleeve l8 may be locked thereto at its ends by means of screw pins I9. For purposes of emphasis it will be noted that the inner guide sleeve I6, the guide sleeve plugs I2 and I4, and the outer guide sleeve I6 are all locked together and to the end or cover plates I and 2, and do not move.

At 20 is the intermediate worm illustrated in full detail in Figures '7 and 8. It consists of a cylindrical member having a central bore which is provided with a. single right hand thread or worm 2i) having a 4 inch lead. The periphery of the intermediate worm is provided with a single right hand thread or worm 20 having a 4 inch lead. The end faces of the intermediate worm are provided with an annular groove 20 for a purpose to be described later. This intermediate worm surrounds the sleeve I6 and is journaled on the ball bearings 50 and has a groove 20 at each end in which part of the races for the thrust bearings are mounted.

Disposed at the ends of the intermediate worm are the thrust rings 2I and 22 which are shown in full detail in Figures 3 and 4 and 16 and 17 respectively. Each of these rings is of annular form flanged on one face, and of semicircular cross section. The ring 2| has an annular groove 2| on its face positioned to take the other race of the ball thrust bearing 2| at the right hand end of the intermediate worm. This ring has a series of threaded holes 2| in one face thereof by means of which it is securely locked to the guide sleeve plug H by means of screws which pass through the disc part of the plug and into the threaded holes in the manner illustrated in connection with the other thrust ring 22 at the left hand end of the intermediate worm, where there is shown in Figure 1 one of the screws 23 by means of which the plug I2 is attached to the ring 2|. These screws 23 engage the threaded holes 22 of the ring 22. This ring has an annular groove 22 which receives the other race of the thrust bearings 24 at the left hand end of the intermediate worm.

The 'outer casing or drum of the device is illustrated as composed of the left and right hand portions 25 and 26. drum is fully illustrated in Figures 18 and 19. The right hand portion has not been duplicated in the drawings since it is the same as the left hand portion with the exception that it has an annular ridge 26 on the face of the flange 26, as shown in Figure 1, aligned with the annular groove 25 on the face of the flange 25 of the left hand section 25 of the drum. The outer ends of the drum sections 25 and 26 are provided with the flanges 25 and 26 respectively. A portion of the inner surface of these drums when united is provided with a single left hand thread or worm having an 18 inch lead. Each drum portion is provided with this thread or groove in a manner so that the pairs match up to provide a continuous thread or groove on the inner face of the assembled drum. The thread or groove for the left hand section is shown at 25 in Figures 18 and 19. The two drum sections are united by screws which pass through the abutting flanges 25 and- 26 as is clear from Figure 1. Together they form a casing which completely surrounds certain of the members, as is clear from Figure 1, which casing is journaled on the guide sleeve plugs by means of the ball bearings 21 so thatit may rotate thereon. As illustrated in Figure 1. the outer surface of the drum sections is provided with a helical groove 25 and 26 on which the hoist cable may be wound in a uniform layer. However, the periphery of the drum may be entirely smooth, and for this reason this variation has been shown on the drum section in Figure 19. Other forms of surfaces can be employed. However, if the drum is to be employed as a pulley it would have a smooth surface as illustrated in Figure 19, so that a belt can be driven from it.

Secured in the concave groove on the face of the disc of each of the guide sleeve plugs are five clrcumferentially spaced thrust plates which have been fully illustrated in Figures 5 and 6. These thrust plates are segmental in form and are concavo-convex in cross section, as is clear from Figure 6. Each has a pair of holes 29 so that screws may be passed through the holes 2| and 22 and the thrust rings 2| and 22 so that the thrust plates are secured thereto to form channels, as is clear from Figure 15. In view of the transverse curvature of the grooves I2 and M (see Figure. 1) and the groove in the disc portion I4 and the other guide sleeve (not shown) and the cross sectional form of the thrust which are shown mainly in dotted line in Figure 15 are of uniform width and depth, but are longitudinally curved. These longitudinally curved channels are radially aligned with the grooves I6 and I8 of the sleeves I6 and I8to form continuations of these grooves at each end thereof.

Lying in the longitudinally curved grooves between the thrust plates 28 and in the slots I6 and I8 of the sleeves I6 and I8 are a series of hardened steel balls 50. As is clear from Fig- The left hand portion of the plates (see Figure 6), the channels between them, v

these balls lie in the helical groove l-l of shaft I I V and in the helical groove 20 in the bore of the intermediate worm 20. They lie in the longitudinally curved channels between the thrust plates 28 which are formed at the sides by the '10 thrust plates 2| and at the top and bottom by the discs l2 and 21, and M and 22respectlvely. These balls also lie in-the helical groove 20 on the outer surface of the intermediate .worm 20 and the helical groove 25 and the correspond-- ing groove in the right hand drum section 26,

which spiral groove is on the inner face of the drum sections. In the structure illustrated these balls are inch in diameter, and of course all of the grooves, channels and slots in which they ride are suitably proportioned to accommodate them. The balls of each ring' form a substantially continuous flexible chain with a very slight clearance between each of them so as to prevent binding, and yet provide a substantially continuous arrangement, that is there are no major gaps between any pair of adjacent balls.

In the operation of the device when the electric motor 1--8 is energized, shaft H is caused to rotate in the bearings 9 and I0. Its rotation will cause the balls incontact therewith to advance depending on both the direction of the thread II and the direction of rotation of shaft l I. For purposes of description it will be assumed that the balls in contact with the thread II in Figure l are moving to the left. As they move to the left they will cause the inner worm 20 to revolve because of their engagement with the thread 2|] on the inner bore thereof. Since these threads are right hand with respect to the 40 threads I I as they are forced along the intermediate worm 20 will be caused to revolve in a direction opposite to the direction of rotation of shaft I l. Those balls in the groove 20 on the periphery of the intermediate worm will move to the right (Figure 1), and as they move will cause the drum 25-24 to revolve in the opposite direction because the threads 25 thereof extend in the opposite direction to the threads 20 of the intermediate worm. The balls in the longitudinally curved passages at each end of the device will move along at the same speed as the balls in the top and bottom horizontal r ws, but move freely through these channels ce they are smooth walled. Thus the balls f each of the five rings travel in a path which comprises alternate sections which are straight and longitudinally curved. Because of the different pitch of the threads on the various members a substantial reduction in speed of the drum 25-28 with respect to the shaft I l results. With the particular pitch of the threads as mentioned above a a speed reduction of 36 to 1 results.

From the above description it will be apparent that the principles of this invention may be embodied in many other physical forms without departure from the scope thereof. Thus, the principles of the invention may be employed in a device which effects a single speed reduction as distinguished from the double speed reduction effected where there is a driving connection between the intermediate worm and the drum, as is the case of the mechanism here illustrated in detail. I do not, therefore, desire to be strictly limited to the disclosure as given for purposes of illustration, but rather to the scope of the appended claims.

What I seek to secure by United States Letters Patent is:

1. In a device of the type described the combination comprising a driving member having a helical groove on its surface, an apertured driven member surrounding the driving member and aperture, a sleeve lying between the driving member and the driven member having a plurality of longitudinal slots in the wall thereof, means forming passages which are continuations of said slots and closed on themselves, and a plurality of balls in each of said slots and passages to form continuous chains.

2. In a device of the type describedthe combination comprising a driving member having a helical groove on its surface, an apertured driven membersurrounding the driving member and having a helical groove on the inner face of its aperture, a sleeve lying between the driving member and the driven member having a plurality of longitudinal slots in the wall thereof, means forming passages which are continuations of said slots and closed on themselves, and a plurality of balls in each of said slots and passages to form continuous chains, the helical grooves on the driving and driven members extending in opposite directions.

3. In a device of the type described the combi nation comprising a driving member having a helical groove on its surface, an apertured driven member surrounding the driving member and having a helical groove on the face of its aperture opposite the groove on the driving member, a sleeve interposed between said members having .a plurality of longitudinal slots in the wall thereof,

means forming channels which are continuations of theslots at each end, a sleeve surrounding the driven 'member having a series of slots radially aligned with the slots of the first mentioned move.

1. In a device of the type described the combination comprising a driving member having 9.

having a helical groove on the inner face of its helical grooveon its surface, an apertured driven .member and surrounding them, "the first driven member having a helical groove on its periphery and the second driven member having a helical groove on the inner face thereof, and a plurality of groups of balls lying in the slots of said sleeves and said channels to form continuous chains thereof, the slots of the sleeves and said channels 5. In the combination of claim 3, means for being arranged to form a series of closed paths preventing movement of said sleeves.

along which the balls of the respective groups 6. In the combination of claim 4, means 101" move, each pair of cooperating helical grooves expreventing movement of said sleeves.

5 tending in opposite directions with respect to each other. PRESTON WHITCOMB. 

